[Edge] Controller.TimeOfUseTariff: add balancingGridSetpoint to configure Power Setpoint during BALANCING

[xlukem]

Summary

As proposed in the OpenEMS community thread:
https://community.openems.io/t/balancing-grid-setpoint-in-time-of-use-controller-wahrend-balancing-state/10793

This PR introduces the balancingGridSetpoint config parameter inside the TimeOfUseTariff Controller to keep a steady Power Setpoint during the BALANCING state. This functionality was previous to Release 2026.2.0 achievable by using the Balancing Controller when scheduled after the TimeOfUseTariff Controller but has since been removed.

Motivation

Enables use cases where the target state is not "Net Zero", such as maintaining a specific buffer for high-dynamic loads.

Changes

TimeOfUseTariffController

• Added balancingGridSetpoint Config Parameter
• using it inside calculateAutomaticMode()

final var pwrBalancing = gridActivePower + essActivePower - balancingGridSetpoint;
...
case BALANCING -> new ApplyMode(BALANCING, pwrBalancing);

TimeOfUseTariffController EnergyScheduler

• introducing it into the EnergyScheduler to improve perfomance of the optimization

var balancingGridSetpointEnergy = period.duration().convertPowerToEnergy(balancingGridSetpoint);
applyBalancing(ef, balancingGridSetpointEnergy);
...
public static void applyBalancing(EnergyFlow.Model model, int balancingGridSetpointEnergy) {
    int target = -model.getSurplus() - balancingGridSetpointEnergy;
    model.setEss(target);
}

Added Tests for TimeOfUseTariffController and Edge.Energy

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Impact

• restores flexibility that existed before 2026.2.0 release
• more advanced control strategies with improved energy scheduler optimization